Lyme disease, a bacterial infection spread through ticks that can cause damage to the joints, heart and nervous system if left untreated, has been linked in a new study to another concern: obsessive-compulsive symptoms (OCS).

Like it or not, your body is teeming with trillions of bugs — microbial cells, that is. Thinking about these bacteria and other microorganisms that you host both outside and inside your body might leave you feeling queasy, but they’re actually critical to maintaining your health, from your weight to your mood.

If you’ve ever pumped gas in the United States, you’ve seen the sticker: “This product may contain up to 10 percent ethanol by volume,” declares one at a Massachusetts Shell station. Since 2005, Washington has mandated that an increasing amount of ethanol be mixed into gasoline every year, encouraging refiners and retailers with cash incentives.

Author Michael Pollan discussed the Farm Bill’s far-reaching impact on the U.S. food system and the environment, how journalists can better cover food policy, and more during a visit to Harvard’s Shorenstein Center on Media Politics and Public Policy. Below are the highlights:

Evidenced by the rapidly growing salmon-farm industry, salmon is one of the world’s most popular fish. The volume of farmed Atlantic salmon increased almost 1,000 percent between 1990 and 2015, according to United Nations statistics; 75 percent of all the salmon we eat is farm-raised. Wild-caught salmon, meanwhile, has become a luxury; it’s harder to find and generally more expensive.

Fires have always burned in the planet’s temperate forests. They hasten regeneration by thinning undergrowth and fertilizing the soil. Before there were humans to flick cigarette butts into the brush, there were lightning storms and cyclical droughts.

For almost a decade, residents of some Pennsylvania counties have complained that the natural gas prospectors nearby have contaminated their water. Locals say that after the fracking for gas began, the water made them sick, that it turned brown, even that it became flammable.

Legislation like the Clean Water Act has helped check the effluent flowing into rivers and streams. Though that fight is far from over, a new, all-too-modern danger has meanwhile seeped invisibly into waters around the world: legal and illegal drugs. And their effect on the ecosystem is poorly understood.

Each year as the weather warms, crowds of families and tourists flock to the beaches. People sometimes don’t realize the risk they take when they enter the ocean, a vast aquatic habitat. Newsrooms in coastal communities are well aware that when humans and wildlife interact, the results can be tragic – especially when sharks make an appearance. Even a minor run-in with a shark can send someone to the emergency room for surgery and stitches.